Airflow and pressure,
sized in seconds.
Enter an opening size and approach wind speed, pick a Pantheon profile, and get free area, volumetric airflow and pressure drop. The same methodology behind our CFD-tested AS/NZS 4740 ratings, for preliminary specification.
Type a size. Read the airflow.
Results update as you type. Profile presets load each system's free open area and K factor; open the override to model a custom free area.
Override FOA & K factor
Indicative only, per AS 4740:2025 at ρ 1.2 kg/m³. Confirm project figures with Invicta.
The maths behind the numbers.
Free open area and K factor are the CFD-derived (ANSYS) values behind each Pantheon profile's AS/NZS 4740 rating. Figures here are for preliminary sizing at standard air density; for tender or compliance, contact Invicta for project-specific data.
The questions we get asked.
What is free open area?
Free open area (FOA) is the proportion of the louvre face that air can actually pass through, once the blade material is subtracted. A 62.5% FOA means 62.5% of the opening is open path. It is the single biggest driver of how much air a louvre will move.
Which profile should I start with?
Zeus for the highest airflow on a 150mm blade, Thor where rain defence matters on a 100mm blade, Odin where you want the lowest pressure loss and a tight blade rhythm, Magni for compact ducted and plant applications, and Loki where the priority is screening rather than rated airflow. Zeus Hydra trades free area for Class A rain defence.
Can I use these numbers for compliance?
Treat them as preliminary sizing. The free area and K factors are our tested figures, but a mechanical submission should be confirmed against project-specific data. Send us the opening schedule and we will size it with you.
What if I know my own free area?
Open the "Override FOA & K factor" panel and enter your own values. The airflow and pressure outputs recalculate against whatever free area and K factor you set.